Photocatalysis provides a promising solution to the worldwide shortages of energy and industrially important raw materials by utilizing sunlight for coupled hydrogen(H_(2))production with controllable organic transfor...Photocatalysis provides a promising solution to the worldwide shortages of energy and industrially important raw materials by utilizing sunlight for coupled hydrogen(H_(2))production with controllable organic transformation.Herein,we demonstrate that PtFeNiCoCu high-entropy alloy(HEA)nanocrystals can act as efficient cocatalysts for H_(2)evolution coupled with selective oxidation of cinnamyl alcohol to cinnamaldehyde by cubic cadmium sulfide(CdS)quantum dots(QDs)with uniform sizes of 4.0±0.5 nm.HEA nanocrystals were prepared via a simple solvothermal approach,and were successfully integrated with CdS QDs by an electrostatic self-assembly method to construct HEA/CdS composites.The optimized HEA/CdS sample presented an enhanced photocatalytic H_(2)production rate of 7.15 mmol g^(-1)h^(-1),which was 13 times that of pure CdS QDs.Moreover,a cinnamyl alcohol conversion of 96.2%with cinnamaldehyde selectivity of 99.5%was achieved after photoreaction for 3 h.The integration of HEA with CdS QDs extended the optical absorption edge from 475 to 484 nm.From d-band center analysis,Pt atoms in the HEA are the active sites for H_(2)evolution,exhibiting higher catalytic activity than pure Pt.Meanwhile,the band structure of the CdS QDs enables the oxidative transformation of cinnamyl alcohol to cinnamaldehyde with high selectivity.Moreover,femtosecond transient absorption spectroscopy shows that HEA can significantly promote the separation of photogenerated carriers in CdS,which is vital for achieving enhanced photocatalytic activity.This work inspires atomic-level design of photocatalytic materials for coordinated production of green energy carriers and value-added products.展开更多
S-scheme heterojunctions have gained widespread application in photocatalytic reactions due to their dis-tinctive carrier transport mechanism and remarkable redox capabilities.However,a significant challenge persists ...S-scheme heterojunctions have gained widespread application in photocatalytic reactions due to their dis-tinctive carrier transport mechanism and remarkable redox capabilities.However,a significant challenge persists in extending carrier lifetimes while simultaneously enhancing light absorption,both of which are essential for optimizing photocatalytic activity.Herein,we report the solvothermal synthesis of ul-trathin CdS nanosheets grown in situ on two-dimensional(2D)Ni-MOF to construct 2D/2D S-scheme heterojunctions.Comprehensive characterizations reveal that the incorporation of Ni-MOF(metal-organic framework)with ligand-to-metal charge transfer(LMCT)states not only broadens optical absorption but also significantly prolongs carrier lifetimes.This synergistic enhancement,coupled with the S-scheme charge transport mechanism,enables the composite to function as a bifunctional catalyst for photocat-alytic hydrogen production and simultaneous benzylamine coupling.The optimal system demonstrates an impressive hydrogen evolution rate of 8.5 mmol g^(-1) h^(-1) and an N-benzylidenebenzylamine yield of 4.6 mmol g^(-1) h^(-1) without requiring a cocatalyst.This work underscores the potential of integrating MOFs with LMCT states into S-scheme heterojunctions to enhance interfacial charge transfer,offering valuable insights for the design of S-scheme heterojunctions for artificial photosynthesis and related fields.展开更多
Photocatalysts show broad application potential in clean energy conversion by utilizing solar energy for chemical transformations[1–3].However,single-component photocatalysts are severely limited in practical applica...Photocatalysts show broad application potential in clean energy conversion by utilizing solar energy for chemical transformations[1–3].However,single-component photocatalysts are severely limited in practical applications due to narrow light absorption ranges and high recombination rates of photogenerated carriers[4].S-scheme heterojunctions preserve optimal redox potentials,offering broad application prospects in solar energy conversion and environmental remediation[5,6].Since photocatalytic reactions occur predominantly at the material interface,a spatially resolved investigation of charge transfer is essential for understanding carrier dynamics at the nanoscale[7].In this context,the highlighted study employs Kelvin probe force microscopy(KPFM)to elucidate the real-space charge-transfer mechanisms in CdS/BiOBr S-scheme heterojunctions,providing direct and quantitative insight into interfacial charge behavior[8].展开更多
Graphitic carbon nitride is flourishing in photocatalytic hydrogen production.However,the performance of traditional carbon nitride materials is limited by their scarcity of surface reactive sites and fast re-combinat...Graphitic carbon nitride is flourishing in photocatalytic hydrogen production.However,the performance of traditional carbon nitride materials is limited by their scarcity of surface reactive sites and fast re-combination of photogenerated electron-hole pairs.Herein,we introduce a simple ultrasonic synthesis method that exfoliates bulk carbon nitride into nanosheets while simultaneously forming S-scheme het-erojunctions with in-situ grown thiophene-based polymer throughπ-πinteractions.The obtained car-bon nitride nanosheet/polymer S-scheme heterojunction possesses abundant surface active sites and ex-hibits suppressed recombination of photogenerated electron-hole pairs,resulting in a hydrogen produc-tion rate approximately double that of bulk carbon nitride and a superior apparent quantum yield of 5.00%.The S-scheme charge transfer mechanism was proven by in-situ irradiated X-ray photoelectron spectroscopy,and time-resolved femtosecond-transient absorption analysis clarified the charge separa-tion and transfer dynamics.This study demonstrates that combining organic semiconductors and hy-percrosslinked polymers is a promising strategy for designing highly efficient S-scheme heterojunction photocatalysts.展开更多
Hydrogen peroxide(H_(2)O_(2)),as an essential and green chemical,is extensively used in energy and environmental applications.However,the production of H_(2)O_(2)primarily relies on the anthraquinone method,which is a...Hydrogen peroxide(H_(2)O_(2)),as an essential and green chemical,is extensively used in energy and environmental applications.However,the production of H_(2)O_(2)primarily relies on the anthraquinone method,which is an energy-intensive method involving multi-step reactions,producing harmful by-product wastes.Solar-driven H_(2)O_(2)production,an alternative route for H_(2)O_(2)generation,is a green and sustainable technology since it only utilizes water and oxygen as feedstock.However,the rapid recombination of charge carriers as well as insufficient redox capability limit the photocatalytic H_(2)O_(2)production performance.Constructing step-scheme(S-scheme)heterojunction photocatalysts has been regarded as an effective strategy to address these drawbacks because it not only achieves spatially separated charge carriers,but also preserves redox capability of the photocatalytic system.This paper covers the recent advances of S-scheme heterojunction photocatalysts for H_(2)O_(2)production in terms of basic principles,characterization techniques,and preparation strategies.Moreover,the mechanism and advantages of S-scheme heterojunction for photocatalytic H_(2)O_(2)generation are systematically discussed.The recent S-scheme heterojunction designs,including inorganic-organic heterojunction,inorganic-inorganic heterojunction,and organic-organic heterojunction,are summarized.Lastly,the challenges and research directions of S-scheme photocatalysts for H_(2)O_(2)generation are presented.展开更多
Two-dimensional(2D)heterojunctions are promising photocatalysts for hydrogen production due to their unique ability to efficiently convert solar energy to green fuels.In this work,an S-scheme 2D/2D FTiO_(2)/CdS hetero...Two-dimensional(2D)heterojunctions are promising photocatalysts for hydrogen production due to their unique ability to efficiently convert solar energy to green fuels.In this work,an S-scheme 2D/2D FTiO_(2)/CdS heterostructure was designed and synthesized via a facile hydrothermal method.The hydrogen evolution rate of optimal F-TiO_(2)/CdS photocatalyst irradiated with simulated sunlight reached to 1.7 mmol g^(−1) h^(−1),which was about 7 times that of pristine CdS nanosheets,1.5 times that of TiO_(2) nanoparticles composited with CdS nanosheets,and the apparent quantum efficiency at 420 nm was 4.3%.The insitu Kelvin probe force microscopy results showed that the built-in electric field strength(BIEF)of 2D/2D F-TiO_(2)/CdS is about 6.2×10^(3) V cm^(−1) under the dark condition,which is about 2.3 times that of TiO_(2) nanoparticles composited with CdS nanosheets.Moreover,in-situ electron paramagnetic resonance results showed that the valence band position of F-TiO_(2) is more positive and showed a clear signal peak,suggesting that F-TiO_(2) could generate more hydroxyl radicals.When F-TiO_(2) contacts with CdS,the signals of both radicals are significantly enhanced,indicating that the reducing ability of CdS and the oxidizing ability of F-TiO_(2) are well preserved.These results verify that S-scheme 2D/2D F-TiO_(2)/CdS processes stronger BIEF,which could effectively enhance the photocatalytic hydrogen production activity.展开更多
Formaldehyde(HCHO),a significant indoor air pollutant,poses serious health risks to humans,making its removal a critical issue.Among the various methods for HCHO elimination,catalytic oxidation has emerged as one of t...Formaldehyde(HCHO),a significant indoor air pollutant,poses serious health risks to humans,making its removal a critical issue.Among the various methods for HCHO elimination,catalytic oxidation has emerged as one of the most efficient and practical approaches.In this study,hierarchical hollow nickel oxide nanofibers(NiO–HNF)are developed by using a semi-sacrificial template-assisted hydrothermal and calcination process.Platinum(Pt)nanoparticles are then loaded onto the NiO–HNF through an impregnation-chemical reduction process.The Pt/NiO–HNF nanocomposite demonstrates a marked improvement in HCHO decomposition activity at room temperature,which can be ascribed to its distinct structural features.The hierarchical structure of the nanocomposite,which provides a high specific surface area and abundant porosity,facilitates the uniform dispersion of Pt nanoparticles and increases the number of active sites available for catalysis.To further investigate the oxidation mechanism,in-situ diffuse reflectance infrared Fourier transform spectroscopy(in-situ DRIFTS)is utilized.The findings suggest that the main intermediates during the oxidation process are dioxymethylene and formate species.This study highlights the potential of hollow transition metal oxide composites as efficient materials for the removal of indoor air pollutants.展开更多
光催化二氧化碳还原成烃类化合物是解决能源短缺和环境污染的重要途径。而构建复合物光催化剂可以有效地解决单一光催化剂的缺点,并且提高二氧化碳还原活性。尽管对复合物光催化剂已经做了很多研究,然而对其活性增强的内在机制还缺乏理...光催化二氧化碳还原成烃类化合物是解决能源短缺和环境污染的重要途径。而构建复合物光催化剂可以有效地解决单一光催化剂的缺点,并且提高二氧化碳还原活性。尽管对复合物光催化剂已经做了很多研究,然而对其活性增强的内在机制还缺乏理论认识。本文采用密度泛函理论计算方法研究了二维/二维BP/g-C_(3)N_(4)复合模型的电子性质和CO_(2)还原反应过程。通过对能带位置和界面电子相互作用的综合分析发现,在BP/g-C_(3)N_(4)异质结中,光生载流子的迁移遵循S型异质结光催化机制。与单一的g-C_(3)N_(4)相比,这种异质结可以实现光生载流子的高效分离并且拥有良好的氧化还原能力。此外,通过对比研究CO_(2)在g-C_(3)N_(4)和BP/g-C_(3)N_(4)还原反应过程发现,异质结使CO_(2)还原反应的最大能垒从1.48 e V降低到1.22e V。因此,BP/g-C_(3)N_(4)异质结在理论上被证明是一种优良的CO_(2)还原光催化剂。这项工作有助于了解BP改性对g-C_(3)N_(4)光催化活性的影响,也为其他高性能CO_(2)还原光催化剂的设计提供理论依据。展开更多
Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-sc...Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-scheme photocatalysts were synthesized using electrospinning and calcination methods.The as-prepared SCN/TiO2 composites showed superior photocatalytic performance than pure TiO2 and SCN in the photocatalytic degradation of Congo Red(CR)aqueous solution.The significant enhancement in photocatalytic activity benefited not only from the 1D well-distributed nanostructure,but also from the S-scheme heterojunction.Furthermore,the XPS analyses and DFT calculations demonstrated that electrons were transferred from SCN to TiO2 across the interface of the SCN/TiO2 composites.The built-in electric field,band edge bending,and Coulomb interaction synergistically facilitated the recombination of relatively useless electrons and holes in hybrid when the interface was irradiated by simulated solar light.Therefore,the remaining electrons and holes with higher reducibility and oxidizability endowed the composite with supreme redox ability.These results were adequately verified by radical trapping experiments,ESR tests,and in situ XPS analyses,suggesting that the electron immigration in the photocatalyst followed the S-scheme heterojunction mechanism.This work can enrich our knowledge of the design and fabrication of novel S-scheme heterojunction photocatalysts and provide a promising strategy for solving environmental pollution in the future.展开更多
Sunlight-driven photocatalytic water-splitting for hydrogen(H2)evolution is a desirable strategy to utilize solar energy.However,this strategy is restricted by insufficient light harvesting and high photogenerated ele...Sunlight-driven photocatalytic water-splitting for hydrogen(H2)evolution is a desirable strategy to utilize solar energy.However,this strategy is restricted by insufficient light harvesting and high photogenerated electron-hole recombination rates of TiO2-based photocatalysts.Here,a graphene-modified WO3/TiO2 step-scheme heterojunction(S-scheme heterojunction)composite photocatalyst was fabricated by a facile one-step hydrothermal method.In the ternary composite,TiO2 and WO3 nanoparticles adhered closely to reduced graphene oxide(rGO)and formed a novel S-scheme heterojunction.Moreover,rGO in the composite not only supplied abundant adsorption and catalytically active sites as an ideal support but also promoted electron separation and transfer from the conduction band of TiO2 by forming a Schottky junction between TiO2 and rGO.The positive cooperative effect of the S-scheme heterojunction formed between WO3 and TiO2 and the Schottky heterojunction formed between TiO2 and graphene sheets suppressed the recombination of relatively useful electrons and holes.This effect also enhanced the light harvesting and promoted the reduction reaction at the active sites.Thus,the novel ternary WO3/TiO2/rGO composite demonstrated a remarkably enhanced photocatalytic H2 evolution rate of 245.8μmol g^-1 h^-1,which was approximately 3.5-fold that of pure TiO2.This work not only presents a low-cost graphene-based S-scheme heterojunction photocatalyst that was obtained via a feasible one-step hydrothermal approach to realize highly efficient H2 generation without using noble metals,but also provides new insights into the design of novel heterojunction photocatalysts.展开更多
Semiconductor heterojunction photocatalysts have received much concern due to their great application prospect in solar energy utilization and conversion.Rational construction of heterostructure with two or more semic...Semiconductor heterojunction photocatalysts have received much concern due to their great application prospect in solar energy utilization and conversion.Rational construction of heterostructure with two or more semiconductor materials can integrate the advantages of multi-components to simultaneously improve the photo-induced charges separation,extend visible light absorption range and retain the high redox ability of photocatalysts.Recently,constructing of g-C3 N4-based heterostructure has become a hot focus due to the multiple merits of g-C3 N4,such as facile synthesis,high stability,unique optical and electronic characteristics.This review tries to give a comprehensive introduction and provide the possible tendency in design and fabrication of g-C3 N4-based heterojunction photocatalysts,especially in rational synthesis of type-II heterojunction,direct Z-scheme heterojunction,new type of S-scheme heterojunction,p-n heterojunction and Schottky heterojunction.Furthermore,the special charges transfer mechanisms of g-C3 N4-based heterojunctions are discussed and their potential applications in photocatalytic water splitting,photo-degradation of contaminants and photo-reduction of CO2 into fuels are also summarized.Finally,we attempt to propose some crucial issues based on the current research,which should be further investigated and resolved in this interesting research area.展开更多
Coronary artery disease （CAD） is a multifactorial disease in which inflammation plays a central role. This study aimed to investigate the association of inflammatory markers such as the neutrophil to lymphocyte rat...Coronary artery disease （CAD） is a multifactorial disease in which inflammation plays a central role. This study aimed to investigate the association of inflammatory markers such as the neutrophil to lymphocyte ratio （NLR）, the Global Registry of Acute Coronary Events （GRACE） score with in-hospital mortality of elderly patients with acute myocardial infarction （AMI） in an attempt to explore the prognostic value of these indices for elderly AMI patients. One thousand consecutive CAD patients were divided into two groups based on age 60. The laboratory and clinical characteristics were assessed retrospectively by reviewing the medical records. The NLR and GRACE score were calculated. In the elderly （〉60 years）, patients with non-ST-elevation myocardial infarction （NSTEMI） and ST-elevation myocardial infarction （STEMI） had significantly higher NLR than did those with unstable angina （UA） and stable angina pectoris （SAP） （P〈0.01）. The NLR was considerably elevated in older AMI patients compared with their younger counterparts （〈60 years） （P〈0.05）. In elderly AMI patients, the NLR was considerably higher in the high-risk group than in both the low-risk and mediumrisk groups based on the GRACE score （P〈0.05 and P〈0.01, respectively）, and the NLR was positively correlated with the GRACE score （r=0.322, P〈0.001）. Either the NLR level or the GRACE score was significantly higher in the death group than in the surviving group （P〈0.05）. By curve receiver operator characteristic curve （ROC） analysis, the optimal cut-off levels of 9.41 for NLR and 174 for GRACE score predicted in-hospital death [ROC area under the curve （AUC） 0.771 and 0.787, respectively, P〈0.001]. It was concluded that an elevated NLR is a potential predictor of in-hospital mortality in elderly patients with AMI.展开更多
Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow micro...Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.展开更多
文摘Photocatalysis provides a promising solution to the worldwide shortages of energy and industrially important raw materials by utilizing sunlight for coupled hydrogen(H_(2))production with controllable organic transformation.Herein,we demonstrate that PtFeNiCoCu high-entropy alloy(HEA)nanocrystals can act as efficient cocatalysts for H_(2)evolution coupled with selective oxidation of cinnamyl alcohol to cinnamaldehyde by cubic cadmium sulfide(CdS)quantum dots(QDs)with uniform sizes of 4.0±0.5 nm.HEA nanocrystals were prepared via a simple solvothermal approach,and were successfully integrated with CdS QDs by an electrostatic self-assembly method to construct HEA/CdS composites.The optimized HEA/CdS sample presented an enhanced photocatalytic H_(2)production rate of 7.15 mmol g^(-1)h^(-1),which was 13 times that of pure CdS QDs.Moreover,a cinnamyl alcohol conversion of 96.2%with cinnamaldehyde selectivity of 99.5%was achieved after photoreaction for 3 h.The integration of HEA with CdS QDs extended the optical absorption edge from 475 to 484 nm.From d-band center analysis,Pt atoms in the HEA are the active sites for H_(2)evolution,exhibiting higher catalytic activity than pure Pt.Meanwhile,the band structure of the CdS QDs enables the oxidative transformation of cinnamyl alcohol to cinnamaldehyde with high selectivity.Moreover,femtosecond transient absorption spectroscopy shows that HEA can significantly promote the separation of photogenerated carriers in CdS,which is vital for achieving enhanced photocatalytic activity.This work inspires atomic-level design of photocatalytic materials for coordinated production of green energy carriers and value-added products.
基金financially supported by the National Key Re-search and Development Program of China(Nos.2022YFB3803600 and 2022YFE0115900)the National Natural Science Foundation of China(Nos.U24A2071,22278324,22238009,22361142704,22202187,and U23A20102)+1 种基金the National Science Foundation of Hubei Province of China(No.2022CFA001)Key R&D Program Projects in Hubei Province(No.2023BAB113).
文摘S-scheme heterojunctions have gained widespread application in photocatalytic reactions due to their dis-tinctive carrier transport mechanism and remarkable redox capabilities.However,a significant challenge persists in extending carrier lifetimes while simultaneously enhancing light absorption,both of which are essential for optimizing photocatalytic activity.Herein,we report the solvothermal synthesis of ul-trathin CdS nanosheets grown in situ on two-dimensional(2D)Ni-MOF to construct 2D/2D S-scheme heterojunctions.Comprehensive characterizations reveal that the incorporation of Ni-MOF(metal-organic framework)with ligand-to-metal charge transfer(LMCT)states not only broadens optical absorption but also significantly prolongs carrier lifetimes.This synergistic enhancement,coupled with the S-scheme charge transport mechanism,enables the composite to function as a bifunctional catalyst for photocat-alytic hydrogen production and simultaneous benzylamine coupling.The optimal system demonstrates an impressive hydrogen evolution rate of 8.5 mmol g^(-1) h^(-1) and an N-benzylidenebenzylamine yield of 4.6 mmol g^(-1) h^(-1) without requiring a cocatalyst.This work underscores the potential of integrating MOFs with LMCT states into S-scheme heterojunctions to enhance interfacial charge transfer,offering valuable insights for the design of S-scheme heterojunctions for artificial photosynthesis and related fields.
文摘Photocatalysts show broad application potential in clean energy conversion by utilizing solar energy for chemical transformations[1–3].However,single-component photocatalysts are severely limited in practical applications due to narrow light absorption ranges and high recombination rates of photogenerated carriers[4].S-scheme heterojunctions preserve optimal redox potentials,offering broad application prospects in solar energy conversion and environmental remediation[5,6].Since photocatalytic reactions occur predominantly at the material interface,a spatially resolved investigation of charge transfer is essential for understanding carrier dynamics at the nanoscale[7].In this context,the highlighted study employs Kelvin probe force microscopy(KPFM)to elucidate the real-space charge-transfer mechanisms in CdS/BiOBr S-scheme heterojunctions,providing direct and quantitative insight into interfacial charge behavior[8].
基金supported by the National Key Research and Development Program of China(No.2022YFB3803600)the National Natural Science Foundation of China(Nos.52073223,22278324,51932007,22238009 and 22361142704)+1 种基金the Natural Science Foundation of Hubei Province of China(2022CFA001)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(No.CUG22061).
文摘Graphitic carbon nitride is flourishing in photocatalytic hydrogen production.However,the performance of traditional carbon nitride materials is limited by their scarcity of surface reactive sites and fast re-combination of photogenerated electron-hole pairs.Herein,we introduce a simple ultrasonic synthesis method that exfoliates bulk carbon nitride into nanosheets while simultaneously forming S-scheme het-erojunctions with in-situ grown thiophene-based polymer throughπ-πinteractions.The obtained car-bon nitride nanosheet/polymer S-scheme heterojunction possesses abundant surface active sites and ex-hibits suppressed recombination of photogenerated electron-hole pairs,resulting in a hydrogen produc-tion rate approximately double that of bulk carbon nitride and a superior apparent quantum yield of 5.00%.The S-scheme charge transfer mechanism was proven by in-situ irradiated X-ray photoelectron spectroscopy,and time-resolved femtosecond-transient absorption analysis clarified the charge separa-tion and transfer dynamics.This study demonstrates that combining organic semiconductors and hy-percrosslinked polymers is a promising strategy for designing highly efficient S-scheme heterojunction photocatalysts.
文摘Hydrogen peroxide(H_(2)O_(2)),as an essential and green chemical,is extensively used in energy and environmental applications.However,the production of H_(2)O_(2)primarily relies on the anthraquinone method,which is an energy-intensive method involving multi-step reactions,producing harmful by-product wastes.Solar-driven H_(2)O_(2)production,an alternative route for H_(2)O_(2)generation,is a green and sustainable technology since it only utilizes water and oxygen as feedstock.However,the rapid recombination of charge carriers as well as insufficient redox capability limit the photocatalytic H_(2)O_(2)production performance.Constructing step-scheme(S-scheme)heterojunction photocatalysts has been regarded as an effective strategy to address these drawbacks because it not only achieves spatially separated charge carriers,but also preserves redox capability of the photocatalytic system.This paper covers the recent advances of S-scheme heterojunction photocatalysts for H_(2)O_(2)production in terms of basic principles,characterization techniques,and preparation strategies.Moreover,the mechanism and advantages of S-scheme heterojunction for photocatalytic H_(2)O_(2)generation are systematically discussed.The recent S-scheme heterojunction designs,including inorganic-organic heterojunction,inorganic-inorganic heterojunction,and organic-organic heterojunction,are summarized.Lastly,the challenges and research directions of S-scheme photocatalysts for H_(2)O_(2)generation are presented.
基金supported by the National Natural Science Foundation of China(No.22378372).
文摘Two-dimensional(2D)heterojunctions are promising photocatalysts for hydrogen production due to their unique ability to efficiently convert solar energy to green fuels.In this work,an S-scheme 2D/2D FTiO_(2)/CdS heterostructure was designed and synthesized via a facile hydrothermal method.The hydrogen evolution rate of optimal F-TiO_(2)/CdS photocatalyst irradiated with simulated sunlight reached to 1.7 mmol g^(−1) h^(−1),which was about 7 times that of pristine CdS nanosheets,1.5 times that of TiO_(2) nanoparticles composited with CdS nanosheets,and the apparent quantum efficiency at 420 nm was 4.3%.The insitu Kelvin probe force microscopy results showed that the built-in electric field strength(BIEF)of 2D/2D F-TiO_(2)/CdS is about 6.2×10^(3) V cm^(−1) under the dark condition,which is about 2.3 times that of TiO_(2) nanoparticles composited with CdS nanosheets.Moreover,in-situ electron paramagnetic resonance results showed that the valence band position of F-TiO_(2) is more positive and showed a clear signal peak,suggesting that F-TiO_(2) could generate more hydroxyl radicals.When F-TiO_(2) contacts with CdS,the signals of both radicals are significantly enhanced,indicating that the reducing ability of CdS and the oxidizing ability of F-TiO_(2) are well preserved.These results verify that S-scheme 2D/2D F-TiO_(2)/CdS processes stronger BIEF,which could effectively enhance the photocatalytic hydrogen production activity.
基金supported by the Guangxi Science and Technology Major Program(AA24263054)the National Natural Science Foundation of China(52472245 and 22278324).
文摘Formaldehyde(HCHO),a significant indoor air pollutant,poses serious health risks to humans,making its removal a critical issue.Among the various methods for HCHO elimination,catalytic oxidation has emerged as one of the most efficient and practical approaches.In this study,hierarchical hollow nickel oxide nanofibers(NiO–HNF)are developed by using a semi-sacrificial template-assisted hydrothermal and calcination process.Platinum(Pt)nanoparticles are then loaded onto the NiO–HNF through an impregnation-chemical reduction process.The Pt/NiO–HNF nanocomposite demonstrates a marked improvement in HCHO decomposition activity at room temperature,which can be ascribed to its distinct structural features.The hierarchical structure of the nanocomposite,which provides a high specific surface area and abundant porosity,facilitates the uniform dispersion of Pt nanoparticles and increases the number of active sites available for catalysis.To further investigate the oxidation mechanism,in-situ diffuse reflectance infrared Fourier transform spectroscopy(in-situ DRIFTS)is utilized.The findings suggest that the main intermediates during the oxidation process are dioxymethylene and formate species.This study highlights the potential of hollow transition metal oxide composites as efficient materials for the removal of indoor air pollutants.
文摘光催化二氧化碳还原成烃类化合物是解决能源短缺和环境污染的重要途径。而构建复合物光催化剂可以有效地解决单一光催化剂的缺点,并且提高二氧化碳还原活性。尽管对复合物光催化剂已经做了很多研究,然而对其活性增强的内在机制还缺乏理论认识。本文采用密度泛函理论计算方法研究了二维/二维BP/g-C_(3)N_(4)复合模型的电子性质和CO_(2)还原反应过程。通过对能带位置和界面电子相互作用的综合分析发现,在BP/g-C_(3)N_(4)异质结中,光生载流子的迁移遵循S型异质结光催化机制。与单一的g-C_(3)N_(4)相比,这种异质结可以实现光生载流子的高效分离并且拥有良好的氧化还原能力。此外,通过对比研究CO_(2)在g-C_(3)N_(4)和BP/g-C_(3)N_(4)还原反应过程发现,异质结使CO_(2)还原反应的最大能垒从1.48 e V降低到1.22e V。因此,BP/g-C_(3)N_(4)异质结在理论上被证明是一种优良的CO_(2)还原光催化剂。这项工作有助于了解BP改性对g-C_(3)N_(4)光催化活性的影响,也为其他高性能CO_(2)还原光催化剂的设计提供理论依据。
文摘Constructing step-scheme(S-scheme)heterojunctions has been confirmed as a promising strategy for enhancing the photocatalytic activity of composite materials.In this work,a series of sulfur-doped g-C3N4(SCN)/TiO2 S-scheme photocatalysts were synthesized using electrospinning and calcination methods.The as-prepared SCN/TiO2 composites showed superior photocatalytic performance than pure TiO2 and SCN in the photocatalytic degradation of Congo Red(CR)aqueous solution.The significant enhancement in photocatalytic activity benefited not only from the 1D well-distributed nanostructure,but also from the S-scheme heterojunction.Furthermore,the XPS analyses and DFT calculations demonstrated that electrons were transferred from SCN to TiO2 across the interface of the SCN/TiO2 composites.The built-in electric field,band edge bending,and Coulomb interaction synergistically facilitated the recombination of relatively useless electrons and holes in hybrid when the interface was irradiated by simulated solar light.Therefore,the remaining electrons and holes with higher reducibility and oxidizability endowed the composite with supreme redox ability.These results were adequately verified by radical trapping experiments,ESR tests,and in situ XPS analyses,suggesting that the electron immigration in the photocatalyst followed the S-scheme heterojunction mechanism.This work can enrich our knowledge of the design and fabrication of novel S-scheme heterojunction photocatalysts and provide a promising strategy for solving environmental pollution in the future.
基金supported by the National Natural Science Foundation of China(U1705251,21871217,21573170,21433007)the National Key Research and Development Program of China(2018YFB1502001)~~
文摘Sunlight-driven photocatalytic water-splitting for hydrogen(H2)evolution is a desirable strategy to utilize solar energy.However,this strategy is restricted by insufficient light harvesting and high photogenerated electron-hole recombination rates of TiO2-based photocatalysts.Here,a graphene-modified WO3/TiO2 step-scheme heterojunction(S-scheme heterojunction)composite photocatalyst was fabricated by a facile one-step hydrothermal method.In the ternary composite,TiO2 and WO3 nanoparticles adhered closely to reduced graphene oxide(rGO)and formed a novel S-scheme heterojunction.Moreover,rGO in the composite not only supplied abundant adsorption and catalytically active sites as an ideal support but also promoted electron separation and transfer from the conduction band of TiO2 by forming a Schottky junction between TiO2 and rGO.The positive cooperative effect of the S-scheme heterojunction formed between WO3 and TiO2 and the Schottky heterojunction formed between TiO2 and graphene sheets suppressed the recombination of relatively useful electrons and holes.This effect also enhanced the light harvesting and promoted the reduction reaction at the active sites.Thus,the novel ternary WO3/TiO2/rGO composite demonstrated a remarkably enhanced photocatalytic H2 evolution rate of 245.8μmol g^-1 h^-1,which was approximately 3.5-fold that of pure TiO2.This work not only presents a low-cost graphene-based S-scheme heterojunction photocatalyst that was obtained via a feasible one-step hydrothermal approach to realize highly efficient H2 generation without using noble metals,but also provides new insights into the design of novel heterojunction photocatalysts.
基金financially supported by the Natural Science Basic Research Program of Shaanxi(Program No.2019JQ-841)Scientific Research Program Funded by Shaanxi Provincial Education Department(Program No.19JK0376)。
文摘Semiconductor heterojunction photocatalysts have received much concern due to their great application prospect in solar energy utilization and conversion.Rational construction of heterostructure with two or more semiconductor materials can integrate the advantages of multi-components to simultaneously improve the photo-induced charges separation,extend visible light absorption range and retain the high redox ability of photocatalysts.Recently,constructing of g-C3 N4-based heterostructure has become a hot focus due to the multiple merits of g-C3 N4,such as facile synthesis,high stability,unique optical and electronic characteristics.This review tries to give a comprehensive introduction and provide the possible tendency in design and fabrication of g-C3 N4-based heterojunction photocatalysts,especially in rational synthesis of type-II heterojunction,direct Z-scheme heterojunction,new type of S-scheme heterojunction,p-n heterojunction and Schottky heterojunction.Furthermore,the special charges transfer mechanisms of g-C3 N4-based heterojunctions are discussed and their potential applications in photocatalytic water splitting,photo-degradation of contaminants and photo-reduction of CO2 into fuels are also summarized.Finally,we attempt to propose some crucial issues based on the current research,which should be further investigated and resolved in this interesting research area.
基金This project was supported by a grant from Hubei Natural Science Foundation of China （No. 2013CKB011）.
文摘Coronary artery disease （CAD） is a multifactorial disease in which inflammation plays a central role. This study aimed to investigate the association of inflammatory markers such as the neutrophil to lymphocyte ratio （NLR）, the Global Registry of Acute Coronary Events （GRACE） score with in-hospital mortality of elderly patients with acute myocardial infarction （AMI） in an attempt to explore the prognostic value of these indices for elderly AMI patients. One thousand consecutive CAD patients were divided into two groups based on age 60. The laboratory and clinical characteristics were assessed retrospectively by reviewing the medical records. The NLR and GRACE score were calculated. In the elderly （〉60 years）, patients with non-ST-elevation myocardial infarction （NSTEMI） and ST-elevation myocardial infarction （STEMI） had significantly higher NLR than did those with unstable angina （UA） and stable angina pectoris （SAP） （P〈0.01）. The NLR was considerably elevated in older AMI patients compared with their younger counterparts （〈60 years） （P〈0.05）. In elderly AMI patients, the NLR was considerably higher in the high-risk group than in both the low-risk and mediumrisk groups based on the GRACE score （P〈0.05 and P〈0.01, respectively）, and the NLR was positively correlated with the GRACE score （r=0.322, P〈0.001）. Either the NLR level or the GRACE score was significantly higher in the death group than in the surviving group （P〈0.05）. By curve receiver operator characteristic curve （ROC） analysis, the optimal cut-off levels of 9.41 for NLR and 174 for GRACE score predicted in-hospital death [ROC area under the curve （AUC） 0.771 and 0.787, respectively, P〈0.001]. It was concluded that an elevated NLR is a potential predictor of in-hospital mortality in elderly patients with AMI.
基金financially supported by the National Natural Science Foundation of China(NSFC)(Nos.51872220,51932007,51961135303,21871217,U1905215 and U1705251)the National Key Research and Development Program of China(No.2018YFB1502001)the Fundamental Research Funds for the Central Universities(No.WUT:2019IVB050)。
文摘Converting solar energy into chemical energy by artificial photosynthesis is promising in addressing the issues of the greenhouse effect and fossil fuel crisis.Herein,a novel photocatalyst,i.e.CdS/TiO_(2) hollow microspheres(HS),were dedicatedly designed to boost overall photocatalytic efficiency.TiO_(2) nanoparticles were in-situ decorated on the inside and outside the shell of Cd S HS,ensuring close contact between TiO_(2) and CdS.The CdS/TiO2 HS with abundant mesopores inside of the shell boost the light absorption via multiscattering effect as well as accessible to reactions in all directions.The heterojunction was scrutinized and the charge transfer across it was revealed by in-situ irradiated X-ray photoelectron spectroscopy(ISI-XPS).Ultimately,the charge transfer in this composite was determined to follow stepscheme mechanism,which not only facilitates the separation of charge carriers but also preserves strong redox ability.Benefited from the intimate linkage between Cd S and TiO_(2) and the favorable step-scheme heterojunction,enhanced photocatalytic CO_(2) reduction activity was accomplished.The CH4 yield rate of CdS/TiO_(2) reaches 27.85μmol g^(–1) h^(–1),which is 145.6 and 3.8 times higher than those of pristine CdS and TiO_(2),respectively.This work presents a novel insight into constructing step-scheme photocatalytic system with desirable performance.
